1. Field of the Invention
This invention relates to an apparatus for rolling metal foil, cloth, paper, or the like, for calendaring. More particularly, the present invention relates to a rolling apparatus with a magnetic force applied thereto for pressing the workpiece.
2. Description of the Related Art
Referring to FIG. 14, one conventional way of rolling metal foil or cloth for calendaring is explained. Numerals 1, 2 and 3 denote rollers, numerals 5, 6 and 7 denote guide rollers, and numeral 4 denotes a workpiece. The workpiece 4 is guided by the guide rollers 5, 6 and 7 and rolled by the rollers 1, 2 and 3 respectively such that the workpiece 4 is flattened or calendared. Referring to FIG. 15, one conventional way of pressing the workpiece 4 is explained. A hydraulic pump 8 presses a bearing 1a which supports the roller 1 such that the workpiece 4 is pressed between rollers 1 and 2. It is also possible to press upwardly on a bearing 2a which supports the roller 2 such that the workpiece 4 is pressed in between rollers 1 and 2.
However, when rollers 1, 2 and 3 are made of metal, they tend to deflect as shown in FIG. 15 because of the pressure applied to the bearings 1a or 21. So, it is impossible to clamp the workpiece between the rollers with a uniform pressure, resulting in poor performance.
Further, the pressure exerted by the hydraulic pump 8 against the bearings 1a or 2a cannot always be maintained at a constant value, so the unbalanced pressure causes an unbalanced rolling as shown in FIG. 17. When one of the rollers 1, 2 and 3 is of an elastic material, for instance, plastic or the like, its surface is easily scratched resulting in a degraded workpiece.
Further, since a plastic roller is not heat resistant, when the workpiece is heated during the rolling process, a plastic roller will deteriorate. To avoid the aforementioned disadvantages, some detecting means to detect the scratches in the workpieces is required, as well as frequent replacement of the deteriorated roller resulting in a higher manufacturing cost.